U.S. Geological Survey Data Series 254

FGDC Metadata

Home | Acronyms | Contents | Navigation | Profiles | Logs | Metadata | Software

Originator: Arnell S. Harrison
Originator: Shawn V. Dadisman
Originator: James G. Flocks
Originator: Dana S. Wiese
Originator: Lisa L. Robbins
Publication_Date: 2007
Archive of Digital Chirp Seismic Reflection Data Collected During USGS Cruise 06FSH01 Offshore of Siesta Key, Florida, May 2006
Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section
Series_Name: U.S. Geological Survey Data Series
Issue_Identification: 254
Publication_Place: St. Petersburg, FL
Publisher: U.S. Geological Survey
In May of 2006, the U.S. Geological Survey conducted geophysical surveys offshore of Siesta Key, Florida. This report serves as an archive of unprocessed digital Chirp seismic reflection data, trackline maps, navigation files, GIS information, Field Activity Collection System (FACS) logs, observer's logbook, and formal FGDC metadata. Gained digital images of the seismic profiles are also provided.

The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.

The data archived here were collected as part of the USGS Florida Shelf Habitat (FLaSH) Mapping Project.
The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 06FSH01 tells us the data were collected in 2006 for the Florida Shelf Habitat (FLaSH) Mapping Project and the data were collected during the first field activity for that study in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the cruise ID. The naming convention used for each seismic line is as follows: yye##a, where yy is the last two digits of the year in which the data were collected, e is a 1-letter abbreviation for the equipment type (for example, c for Chirp), ## is a 2-digit number representing a specific track, and a is a letter representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems.

The Chirp system uses a signal of continuously varying frequency. The sound source and receiver is a towfish, which is typically flown 2-5 m above the seafloor. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by a receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.125 s) and recorded for specific intervals of time (for example, 50 ms). In this way, a two-dimensional vertical image of the shallow geologic structure beneath the ship track is produced.

The seismic source employed for 06FSH01 Chirp data collection consisted of an EdgeTech SB-424 towfish running Delph Seismic FSSB V. 2.7 software and towed about 17 m behind the GPS antenna. Sample frequency of the data was 25 kHz, and record length was 99 ms. Shot rate was 0.250 s, and shot spacing was about 2 m.

For each recorded shot of the Chirp data, three channels of trace data are collected. Channel 3 is the "real," or in-phase component of the signal, channel 2 is the "imaginary," or quadrature component of the signal, and channel 1 is the "envelope," or product of channels 2 and 3. Only channel 1 was used to produce the profiles presented here. However, all channels are included in the SEG-Y data files.

The unprocessed seismic data are stored in SEG-Y, integer, Motorola format, which is a standard digital format that can be read and manipulated by most seismic processing software packages (Barry and others, 1975). The SEG-Y formatted trace files have a .TRA extension. Additional recording parameters for each trace file can also be found in the .PAR file associated with each .TRA file. However, the .PAR and .PLN files included here are only needed to process or display the data with Delph Seismic software. Also provided are example Seismic Unix scripts that allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 1,000 shots, and produce a gained GIF image of each profile.

The printable profiles provided here are GIF images that were gained using Seismic Unix software. The processed SEG-Y data were exported to Chesapeake Technology, Inc. (CTI) SonarWeb software to produce interactive versions of the profiles that allow the user to obtain a geographic location and depth from the profile for a cursor position. This information is displayed in the status bar of the browser. Note: The only supported Web browsers that properly display all features of the interactive profiles are Internet Explorer 6 for Windows and Firefox 1.5 for all platforms. For all browsers, the status bar and JavaScript must be enabled. Firefox also requires "Change status bar text" to be checked under Advanced JavaScript Settings. Use of other browsers may result in spurious or no information given in the status window. Firefox may be downloaded at http://www.mozilla.org/products/firefox.

Beginning_Date: 20060510
Ending_Date: 20060515
Currentness_Reference: Data collection interval
Progress: Complete
Maintenance_and_Update_Frequency: None planned
West_Bounding_Coordinate: -82.624876
East_Bounding_Coordinate: -82.531654
North_Bounding_Coordinate: 27.265393
South_Bounding_Coordinate: 27.181070
Theme_Keyword_Thesaurus: None
Theme_Keyword: marine seismic reflection
Theme_Keyword: Chirp
Theme_Keyword: SEG-Y
Theme_Keyword: 06FSH01
Theme_Keyword: Florida Shelf and Habitat Mapping
Place_Keyword_Thesaurus: None
Place_Keyword: Florida
Place_Keyword: Siesta Key
Place_Keyword: Sarasota Bay
Place_Keyword: Gulf of Mexico
Access_Constraints: None. These data are held in the public domain.
The U.S. Geological Survey requests to be acknowledged as originator of the data in future products or derivative research.
Contact_Person: Jim. Flocks
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3012
Contact_Electronic_Mail_Address: jflocks@usgs.gov
Browse_Graphic_File_Name: DVD/maps/cruisenav/06fsh01_location.jpg
Location map of all digital Chirp seismic reflection data collected during USGS Cruise 06FSH01. This map was created at a scale of 1:250,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Browse_Graphic_File_Name: DVD/maps/cruisenav/06fsh01_survey.jpg
Trackline map of digital Chirp seismic reflection data collected in the survey area during USGS Cruise 06FSH01. This map was created at a scale of 1:75,000. Refer to the Lineage section below for the trackline map creation process.
Browse_Graphic_File_Type: JPEG
Funding and (or) support for this study was provided by the USGS Coastal and Marine Geology Program. We thank R/V G.K. Gilbert captain Rich Young of the USGS in St. Petersburg, Florida, for his assistance in data collection. This document was improved by the reviews of Ellen Raabe (USGS) and Kate Ciembronowicz (ETI) of the USGS in St. Petersburg, Florida.

The validity or accuracy of marine seismic reflection profiles is highly qualitative and depends on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show any major anomalies. However, only 2 minutes of navigation data were available for line 06c01, therefore, no line navigation map, interactive profile or trackline statistics could be created for this line.
This data set is from one cruise with consistent instrument calibrations.
These data are collected along tracklines (2-D) and are therefore inherently incomplete. Geologic details between lines must be inferred.
As the seismic reflection data were acquired, the position of the vessel was continuously determined by a CSI Wireless DGPS WAAS Max receiver, which is accurate within 1-3 m. Positions were recorded and written to the trace headers in Zone 17 UTMs about every 1 s. Only 2 minutes of navigation data were available for line 06c01; therefore, no line navigation map, interactive profile or trackline statistics were created for this line. The ASCII navigation files and trackline maps have not been corrected to reflect the approximately 17-m offset between the Chirp and GPS antenna. Refer to figure 1 included with this archive (Data Series 254) for a diagram of the acquisition geometry, including the GPS offset measurements. Line navigation maps and interactive profiles generated with CTI SonarWeb software have been corrected for the GPS offset.
These data are not to be used for bathymetry. Depths shown on the Chirp profiles are relative to the depth of the towfish, not to sea level. Furthermore, the raising or lowering of the towfish during a survey (to avoid obstacles or follow relief) produces a relative shift in the multiple reflections seen in the profile, which may be confused as a geologic feature. Any elevation change of the towfish is recorded in the logbooks and is evident on the seismic profiles by steep, abrupt shifts in the seafloor return.
Chirp processing: The SEG-Y data were processed with Seismic Unix to produce GIF images of the seismic profiles included in this report. A representative Chirp data processing sequence consisted of (1) Stripping off channel 1 for each shot and converting to SU format, (2) applying automatic gain control, (3) displaying PostScript, and (4) converting of PostScript image to a GIF image. The processed SEG-Y data were then exported to CTI SonarWeb software to produce an interactive version of each profile that allows the user to obtain a geographic location and depth from the profile for a cursor position. Refer to the Supplemental Information section above for details on how to use the interactive profiles.
Process_Date: 2006
Navigation processing: No navigation was written to the SEG-Y headers for most of line 06c01. However, navigation was collected for a coincident sidescan sonar trackline. This sidescan sonar navigation was merged with the Chirp shotpoints by the recorded time; however, the sidescan sonar line started at shotpoint 1500 and therefore no navigation exists for the first 1499 shots of line 06c01. Shotpoint navigation files and 1,000-shot-interval location files were extracted from the trace headers of each line using Seismic Unix software. These files were then processed with PROJ.4 software (http://www.remotesensing.org/proj) to generate latitude and longitude from UTMs and reformatted for use with Environmental Systems Research Institute (ESRI) GIS software.
Process_Date: 2006
Trackline map creation: The trackline maps provided in this archive were created using the Points to Lines ArcScript (D. Rathert, http://arcscripts.esri.com/details.asp?dbid=12702) along with ESRI ArcGIS 9.1 software and then exported to Adobe Illustrator for further editing. The maps were later converted into JPEG format by Adobe GoLive. The maps are unprojected (geographic coordinates, NAD83). The USGS is the originator of all layers used. A map of trackline navigation for each seismic profile was also produced with CTI SonarWeb software and is in UTM Zone 17 projection.
Process_Date: 2006
Data Series preparation: In addition to the process steps described above, the following steps were taken to produce this Data Series report: the handwritten logs were scanned and saved as PDF files, digital FACS logs were created using the handwritten logs and personal accounts of the crew members and saved as PDF files, and an HTML-based format was used to present the various parts of this archive.
Process_Date: 2006

Horizontal X and Y locations (latitude and longitude and Zone 17 UTMs) for each shot are provided as ASCII text files, along with the date and time (UTC) the shot was recorded.

Latitude_Resolution: 0.000009
Longitude_Resolution: 0.000009
Geographic_Coordinate_Units: decimal degrees
Horizontal_Datum_Name: WGS84
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137
Denominator_of_Flattening_Ratio: 298.257

Binary data file: Trace data are available as binary files in SEG-Y format. These files have a .TRA extension and range in size from 49 to 234 MB.
Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, no. 2, p. 344-352. Also available online at http://www.seg.org/publications/tech-stand.
Zihlman, F.N., 1992, DUMPSEGY V1.0: A program to examine the contents of SEG-Y disk-image seismic data: U.S. Geological Survey Open-File Report 92-590, 28 p.
Graphic image file: Printable profiles are available as GIF images. Interactive profiles are available as HTML pages with accompanying JPEG images. The line navigation maps and trackline maps are JPEG images. The trackline maps contain links to the seismic profiles and line navigation maps.
Navigation file: Navigation files are available as ASCII text files. Provided are raw (unprocessed) shotpoint navigation files, processed shotpoint navigation files, and processed 1,000-shot-interval location files.
GIS file: The GIS project used to create the trackline maps is provided as a zip file composed of ESRI map documents, shapefiles, and metadata.

Contact_Person: Shawn Dadisman
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3029
Contact_Electronic_Mail_Address: sdadisman@usgs.gov
Data may be available on-line only by special arrangement with the distributor above.
Resource_Description: U.S. Geological Survey Data Series 254
This DVD publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

Although all data and software published on this DVD have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and (or) the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data, software, or related materials.

Format_Name: SEG-Y
The SEG-Y standard format (Barry and others, 1975) consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which include information specific to line and reel number; a trace data block that follows the reel identification header, with the first 240 bytes of each trace block consisting of the binary trace identification header; and seismic data samples that follow the trace identification header.
File_Decompression_Technique: None
Transfer_Size: 4100 MB
Offline_Media: DVD
Recording_Format: ISO 9660
Compatibility_Information: UNIX, Linux, DOS, Macintosh
Format_Name: map document, shapefile, metadata
The GIS project used to create the trackline maps is composed of map documents, shapefiles, and metadata. Map documents were created with ESRI ArcGIS 9.1 software. The shapefiles provided may also be viewed using other versions of ArcView, ArcGIS, or public domain software ArcExplorer (http://www.esri.com/software/arcexplorer/).
File_Decompression_Technique: unzip
Transfer_Size: 21.1 MB
Network_Resource_Name: DVD/software/arc/arc.zip
Prices vary.
Publications are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS, e-mail: infoservices@usgs.gov).
Use of SEG-Y data requires specialized seismic processing software, such as public domain software Seismic Unix (http://www.cwp.mines.edu/cwpcodes/).

Metadata_Date: 20061227
Contact_Person: Arnell Harrison
Contact_Organization: ETI, contracted by U.S. Geological Survey
Contact_Position: Geologist
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3111
Contact_Electronic_Mail_Address: aharrison@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

Home | Acronyms | Contents | Navigation | Profiles | Logs | Metadata | Software

Accessibility FOIA Privacy Policies and Notices

Take Pride in America home page. USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubs.usgs.gov/ds/2007/254/html/metadata.html
Page Contact Information: Publishing Services
Page Last Modified: Monday, 28-Nov-2016 12:25:55 EST